JP2002159189A - Piezoelectric actuator and disc recorder comprising it and its controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a piezoelectric actuator in which a strain being generated in the suspension or arm of a main actuator can be detected previously be detecting the strain of the piezoelectric actuator itself and can be fed forward. SOLUTION: The piezoelectric actuator A comprises a piezoelectric element produced by laying a plurality of piezoelectric layers Ra1-Ra4 and a plurality of electrode plates Pa1-Pa5 alternately wherein a part Ra1 of the plurality of piezoelectric layers Ra1-Ra4 and a part Pa1, Pa2 of the plurality of electrode plates Pa1-Pa5 constitute a sensor part for detecting a strain generated in the piezoelectric actuator A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a piezoelectric actuator having a piezoelectric element using a piezoelectric body, a disk recording device incorporating such a piezoelectric actuator, and a method of controlling the disk recording device.

[0002]

2. Description of the Related Art As is well known, a hard disk drive (a so-called HDD; hereinafter abbreviated as appropriate) as a kind of magnetic disk drive is built in a personal computer such as a laptop type or a notebook type. It is widely used as a type external storage device. In such a hard disk device, positioning control of a head for recording information on a magnetic disk and / or reading information recorded on the disk is usually performed by a servo system. In this servo system, the head is positioned at a target position by controlling the drive of an actuator that supports the head and reciprocates in the radial direction of the disk.

[0003] In recent years, as the performance of personal computers has become higher, the demand for smaller and larger-capacity HDDs has been increasing. However, in order to increase the storage capacity of HDDs, it is necessary to increase the capacity of HDDs as recording media. It is required to improve the track density and the linear recording density to increase the recording density of the disk. In order to realize the high recording density, a technique of positioning the head with high accuracy with respect to a target track on a disk is important. For this reason, various contrivances / improvements have been attempted not only for the above-described servo system control technology, but also for the actuating mechanism itself.

One of the major obstacles in accurately controlling the driving of the actuator and positioning the head at a target position with high accuracy is mechanical vibration generated in an actuator component such as a support arm for supporting the head. Is mentioned. Such mechanical vibration of the actuator structure adversely affects a servo system that performs head positioning control, and may cause a malfunction such as off-track. That is, the vibration caused by the actuator structure causes a reduction in the positioning accuracy of the head, and particularly causes a reduction in the recording density (track density) in the track direction. Therefore, it is necessary to reduce the adverse effect on the servo system as much as possible by eliminating mechanical vibrations generated in the actuator mechanism as much as possible and increasing the resonance frequency of the support arm and the like.

In order to increase the track density, it is desirable to reduce the track pitch as much as possible. However, in order to increase the reliability of data recording / reproduction (reduce the probability of occurrence of a read error), It is necessary to improve the track following property of the head (positioning property with respect to the track center). Normally, the track error (off-track amount: three times the standard deviation) needs to be about 0.1 times the track pitch. Further, it is necessary to minimize off-track with respect to external force from a spindle motor as a factor that occurs from outside the HDD or inside the HDD. For this purpose, it is required to increase the frequency of the servo system as much as possible.

As one of these measures, an auxiliary actuator is provided for an actuator (main actuator).
Attempts have been made to cancel the resonance characteristics of the main actuator by controlling the driving of the auxiliary actuator, thereby increasing the frequency of the entire actuator system and increasing the servo frequency. Further, it is considered that a piezoelectric actuator having a piezoelectric element using a piezoelectric body is used as the auxiliary actuator (for example,
See JP-A-11-96697).

FIGS. 13 and 14 are views for explaining the structure of a conventional piezoelectric actuator. FIG.
Has a plurality of piezoelectric layers Rj.
1 to Rj3 and a plurality of electrode plates Pj1 to Pj4 which are alternately stacked. Each piezoelectric layer Rj
1 to Rj3 are a thin plate having a predetermined thickness, that is, a rectangular parallelepiped;
Each of the electrode plates Pj1 to Pj4 has a rectangular thin plate shape.
The overall shape of the piezoelectric actuator J is formed in a substantially rectangular parallelepiped shape, and the piezoelectric layers Rj1 to Rj3 and the electrode plates Pj1 to Pj4 are alternately stacked in the thickness direction of the rectangular parallelepiped.

The terminal portions of the electrode plates Pj1 to Pj4 are connected to each other every other layer. That is,
The electrode plate Pj1 and the electrode plate Pj3 are connected to each other at terminal portions to form a drive electrode Yj1, and the electrode plate Pj2 and the electrode plate Pj3 are connected.
j4 is connected between the terminals to form a drive electrode Yj2. Then, a power supply device Sv is provided between the two drive electrodes Yj1 and Yj2 to constitute a power supply circuit, and an AC signal is applied to the piezoelectric actuator J by the power supply device Sv, so that the piezoelectric layers Rj1 to Rj3 move in the length direction. It is designed to expand and contract to be driven.

On the other hand, also in the case of the piezoelectric actuator K shown in FIG. 14, the whole shape is formed in a substantially rectangular parallelepiped. In this case, however, a plurality of piezoelectric layers Rk1 to RkN and a plurality of electrode plates Pk1 are formed. To Pk (N + 1) are alternately stacked in the length direction of the rectangular parallelepiped. The electrode plate P
k1 to Pk (N + 1) have their terminal portions connected to each other every other layer to form a drive electrode Yk1 and a drive electrode Yk2.
And is composed. The two electrodes Yk1 and Yk2
The power supply device Sv is provided therebetween to form a power supply circuit, and by applying an AC signal to the piezoelectric actuator K by the power supply device Sv, the piezoelectric layers Rk1 to RkN expand and contract in the thickness direction. As a result, the entire piezoelectric actuator K becomes It is driven to expand and contract in the length direction.

[0010]

As a control index for driving the auxiliary actuator, a position error signal with respect to servo data read by a head is usually used.
That is, conventionally, in order to perform position control by the main actuator, servo data recorded on a disk is read by a head, and a position error signal obtained by obtaining a difference from a position to which the head should be moved from the read signal is obtained. The displacement of the head position due to resonance caused by the movement of the main actuator is corrected by the auxiliary actuator.

However, in this method, since the position error signal is used, the control is performed using the result of the movement of the head, and the distortion applied to the suspension or the arm supporting the head is detected in advance and feed forward is performed. Therefore, there was a technical problem that high-speed response was difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above technical problem, and it is intended to detect a distortion of a suspension or an arm of a main actuator in advance by detecting a distortion of a piezoelectric actuator itself, thereby enabling feedforward. Is the basic purpose.

[0013]

In order to solve the above-mentioned problems, a first aspect of the present invention is directed to a piezoelectric device having a piezoelectric element having a plurality of piezoelectric layers and a plurality of electrode plates alternately stacked. In the actuator, a part of the plurality of piezoelectric layers and a part of the plurality of electrode plates constitute a sensor unit for detecting a distortion generated in the piezoelectric actuator. This makes it possible to detect the distortion generated in the piezoelectric actuator. When such a piezoelectric actuator is attached to the main actuator, it is possible to detect distortion occurring in the components of the main actuator.

According to a second aspect of the present invention, there is provided a piezoelectric actuator including a piezoelectric element in which a plurality of piezoelectric layers and a plurality of electrode plates are alternately laminated, wherein the surface electrode plate located on the surface of the piezoelectric element is provided. Another piezoelectric layer and another electrode plate are sequentially disposed on at least a part of the piezoelectric actuator, and the piezoelectric actuator is composed of the surface electrode plate, the another electrode plate, and the another piezoelectric layer located therebetween. And a sensor unit configured to detect a distortion generated in the sensor. This makes it possible to detect the distortion generated in the piezoelectric actuator. When such a piezoelectric actuator is attached to the main actuator, it is possible to detect distortion occurring in the components of the main actuator.

According to a third aspect of the present invention, in the first or second aspect, two sensor units for detecting the distortion are provided. This allows
The rotational component of the distortion can be detected.

According to a fourth aspect of the present invention, there is provided a head for recording information on a disk and / or reading out information recorded on the disk, a suspension for supporting the head, and a rotating shaft for supporting the suspension. A main actuator having a movable support arm for moving the head, the piezoelectric actuator according to any one of claims 1 to 3, and a drive control of the piezoelectric actuator. The present invention is characterized in that the mechanical vibration generated when driving the main actuator is reduced. As a result, the influence of resonance of the suspension, arm and main actuator supporting the head can be removed by the piezoelectric actuator, and a disk recording device capable of moving the position of the head at high speed and with high accuracy is provided.

According to a fifth aspect of the present invention, in the fourth aspect, a plurality of piezoelectric actuators according to the first or second aspect are provided. As a result, the influence of the rotational component of the distortion of the suspension or arm supporting the head or the main actuator can be removed by the piezoelectric actuator, and a disk recording device that can move the position of the head at high speed and with high accuracy is provided.

According to a sixth aspect of the present invention, there is provided a head for recording information on a disk and / or reading information recorded on the disk, a suspension for supporting the head, and a rotating shaft for supporting the suspension. 3. A piezoelectric actuator for controlling the operation of a disk recording device comprising a main actuator having a movable support arm for moving the head and comprising the piezoelectric actuator according to claim 1 or 2. The driving of the piezoelectric actuator is controlled based on an output signal from a sensor unit for detecting distortion of the main actuator, so that mechanical vibration generated when the main actuator is driven is reduced. As a result, the effect of resonance of the suspension, the arm supporting the head, and the main actuator can be removed by the piezoelectric actuator, and a control method of the disk recording apparatus that can move the position of the head at high speed and with high accuracy is provided.

According to a seventh aspect of the present invention, there is provided a head for recording information on a disk and / or reading out information recorded on the disk, a suspension for supporting the head, and a rotating shaft for supporting the suspension. And a main actuator for moving the head having a movable support arm, and controlling the operation of the disk recording device having the piezoelectric actuator according to claim 3 by controlling the two sensor units. The driving control of the piezoelectric actuator is performed based on a signal obtained by subjecting the output signal of the above to a difference processing to reduce the mechanical vibration generated when the main actuator is driven. This provides a control method for a disk recording apparatus that can remove the influence of the rotational component of the distortion of the suspension, arm or main actuator supporting the head by the piezoelectric actuator, and can move the position of the head at high speed and with high accuracy. Is done.

According to an eighth aspect of the present invention, there is provided a head for recording information on a disk and / or reading information recorded on the disk, a suspension for supporting the head, and a rotating shaft for supporting the suspension. And a main actuator for moving the head having a movable support arm, and controlling the operation of a disk recording apparatus including two piezoelectric actuators according to claim 1 or 2. Drive control of the piezoelectric actuator based on a signal obtained by performing differential processing on an output signal from a sensor unit for detecting distortion of each of the two piezoelectric actuators to reduce mechanical vibration generated when the main actuator is driven. Features. This provides a control method for a disk recording apparatus that can remove the influence of the rotational component of the distortion of the suspension, arm or main actuator supporting the head by the piezoelectric actuator, and can move the position of the head at high speed and with high accuracy. Is done.

According to a ninth aspect of the present invention, there is provided a head for recording information on a disk and / or reading information recorded on the disk, a suspension for supporting the head, and a rotating shaft for supporting the suspension. A main actuator for moving the head having a movable support arm, and a piezoelectric actuator having a piezoelectric element as an auxiliary actuator, in which a plurality of piezoelectric layers and a plurality of electrode plates are alternately stacked. When controlling the operation of the disk recording device, the output signal generated in accordance with the distortion generated in the piezoelectric actuator and the signal from the drive source for driving the piezoelectric actuator can be switched to be detected, and the distortion can be detected. Driving the piezoelectric actuator based on an output signal generated in accordance with Wherein the reducing mechanical vibration caused when driving. Thereby, the influence of the resonance of the suspension, arm and main actuator supporting the head can be eliminated even with a normal piezoelectric actuator, and the position of the head can be moved at high speed and with high accuracy. Is provided.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. (Embodiment 1) FIGS. 1A and 1B are a perspective view and a sectional explanatory view of a piezoelectric actuator according to a first embodiment of the present invention. As shown in these figures, the piezoelectric actuator A according to the present embodiment includes a plurality of piezoelectric layers Ra1 to Ra4 and a plurality of electrode plates Pa1 to Pa4.
5 are alternately stacked.
Each of the piezoelectric layers Ra1 to Ra4 is a thin plate having a predetermined thickness, that is, a rectangular parallelepiped, and each of the electrode plates Pa1 to Pa5 is a rectangular thin plate. Each of the piezoelectric layers Ra1 to Ra4 is made of, for example, a PZT-based piezoelectric ceramic, and is subjected to polarization processing such that the polarization direction is reversed for each layer. The piezoelectric actuator A has a substantially rectangular parallelepiped overall shape, and the piezoelectric layers Ra1 to Ra4 and the electrode plates Pa1 to Pa5 are alternately stacked in the thickness direction of the rectangular parallelepiped.

The electrode plates Pa1 to Pa5 correspond to the electrode plates Pa on the actuator surface located at the uppermost position in FIG.
With the exception of 1, the terminals are connected to each other every other layer. That is, the electrode plate Pa2 and the electrode plate Pa4 are connected to each other at the terminal portions to form the drive electrode Ya1,
The electrode plate Pa3 and the electrode plate Pa5 are connected to each other by terminal portions to form a drive electrode Ya2. The power supply device Sv is provided between the two electrodes Ya1 and Ya2 to form a power supply circuit, and an AC signal is applied to the piezoelectric actuator A by the power supply device Sv.
The piezoelectric layers Ra <b> 2 to Ra <b> 4 located between a <b> 2 and a <b> 2 are driven while expanding and contracting in the direction perpendicular to the electric field (that is, the length direction of the piezoelectric actuator A). That is, this is a driving method using the length vibration of the piezoelectric body.

In the present embodiment, the uppermost piezoelectric layer Ra1 in FIG. 1 is used for detecting the distortion of the piezoelectric actuator A. That is, the piezoelectric layer Ra1 is sandwiched between the uppermost surface electrode plate Pa1 and the second uppermost electrode plate Pa2.
a2 and the piezoelectric layer Ra1 constitute a sensor unit for detecting a distortion generated in the piezoelectric actuator A. Thus, the plurality of piezoelectric layers Ra1 to Ra alternately stacked
4 and a part Pa1 and Pa2 of the plurality of electrode plates Pa1 to Pa5 constitute a sensor unit for detecting a distortion generated in the piezoelectric actuator A. When strain is applied to the entire piezoelectric actuator A from the outside, charges corresponding to the strain are generated in the piezoelectric layer Ra1, and the charges can be taken out by the measuring means Mv disposed between the electrodes Pa1 and Pa2 of the sensor section. It has become.

FIG. 2 is an explanatory plan view showing a state where the piezoelectric actuator A described in FIG. 1 is attached to a main actuator of a magnetic disk drive. FIG. 3 is an explanatory plan view schematically showing the configuration of the magnetic disk drive according to the present embodiment. The main actuator 10 supports and moves a head 12 for recording information on the magnetic disk Dm and / or reading information recorded on the disk Dm, and a support arm rotatable about a rotation axis 11a. And an actuator body 11 having a voice coil 15 as a drive source. The above-described piezoelectric actuator A as an auxiliary actuator is attached to the side of the voice coil 15.

A suspension 13 for supporting the head 12 is connected to the distal end of the support arm 14.
Note that a plurality of suspensions and heads can be attached to the support arm 14. The rotating shaft 11a
Is supported by bearing means such as a ball bearing, and the actuator body 11 can freely rotate and swing around the rotating shaft 11a. As a result, the head 12 supported by the tip of the suspension 13 is moved to the disk Dm.
Can be freely reciprocated in the radial direction.

In addition to the above components, the magnetic disk device 1 includes a motor 3 (disk motor) for rotating the magnetic disk Dm, a voice coil motor 5 for driving the voice coil 15, and a disk A control circuit element 7 for controlling the motor 3, the voice coil motor 5, the piezoelectric actuator 10, and the like is provided.

Servo data for indicating position information on the magnetic disk Dm is written on the magnetic disk Dm. While reading the servo data by the head 12, the voice coil motor 5 is controlled by a servo system incorporated in the control circuit element 7, and the actuator main body 11 is rotated about the rotation shaft 11a. That is, the actuator main body 11 is rotationally driven by the voice coil motor 5, and the support arm 14 is integrally driven in the radial direction of the disk Dm. As a result, the head 12 moves in the radial direction of the disk Dm and is positioned at the target position.

While the control circuit element 7 drives the voice coil motor 5 of the main actuator 10 as described above, it also supplies a driving voltage to the piezoelectric actuator A which is an auxiliary actuator. The piezoelectric actuator A is
In response to the supply of the driving voltage, the support arm 14 is excited by expanding and contracting by several microns in the longitudinal direction (the direction of the arrow in FIG. 1) to excite the resonance mode. As a result, the head 12 is driven a minute distance by the driving force generated by the piezoelectric actuator A in the resonance mode. Thus, the resonance generated by driving the voice coil motor 5 is canceled by the resonance generated by driving the piezoelectric actuator A.

FIG. 4 is a block diagram of the magnetic disk drive 1 for explaining a method of controlling the main actuator 10 and the piezoelectric actuator A of the magnetic disk drive 1. The control of the main actuator 10 is as described above.
On the other hand, the piezoelectric actuator A is controlled based on an output signal from the sensor section As that performs distortion detection. As described above, the sensor portion As includes the electrode plates Pa1 and Pa2 of the piezoelectric actuator A and the piezoelectric layer Ra1 sandwiched therebetween.
The output signal from the sensor section As is obtained as a detection signal by the measuring means Mv (see FIG. 1B) disposed between the electrodes Pa1 and Pa2 of the sensor section As. .

The vibration caused by the resonance of the support arm 14 and the suspension 13 accompanying the driving of the main actuator 10,
A distortion is generated in the piezoelectric actuator A, and a detection signal is output from the sensor unit As that has detected the distortion. This sensor section As
Is proportional to the magnitude of the distortion generated in the piezoelectric actuator A. This output signal is input to the control circuit element 7 as control means. The control circuit element 7 transmits a drive signal to the piezoelectric actuator A so as to cancel the distortion according to the output signal.

The driving part Ad of the piezoelectric actuator A shown in FIG.
a1, Ya2 and piezoelectric layers Ra2 to Ra located therebetween
4. The position detecting means 9 detects the position of the head 12 based on an output signal from the head 12, and is preferably provided in the control circuit element 7.

FIG. 5 is a Bode diagram showing the resonance characteristics of the main actuator 10 with and without driving the piezoelectric actuator A. The dashed curve shows the characteristics when the piezoelectric actuator A is not driven, and the solid curve shows the characteristics when the piezoelectric actuator A is driven. As can be clearly understood from this figure, the resonance of the main actuator 10 has disappeared by driving the piezoelectric actuator A. Thereby, the band of the servo system of the main actuator 10 can be set to a higher frequency.

As described above, according to the present embodiment, by detecting the rising of the output signal from the sensor section As, it is possible to predict the resonance vibration and control the driving of the piezoelectric actuator A. Thus, a higher-speed response can be performed as compared with the case where control is performed by detecting a position error signal. As a result, the frequency range of the servo system of the disk device 1 could be expanded, and high-speed response could be performed. In the present embodiment, the magnetic disk drive 1 has been described as an example. However, the piezoelectric actuator according to the present invention is not limited to this. The present invention can be effectively applied to various types of devices.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG. still,
In the following description, components having the same configuration and performing the same operation as those in the first embodiment are denoted by the same reference numerals, and further description is omitted. FIGS. 6A and 6B are a perspective view and a sectional explanatory view showing a piezoelectric actuator B according to a second embodiment of the present invention. Also in the case of the piezoelectric actuator B of this embodiment, the overall shape is formed in a substantially rectangular parallelepiped shape.
In this case, the plurality of piezoelectric layers Rb1 to RbN and the plurality of electrode plates Pb1 to Pb (N + 1) are alternately stacked in the length direction of the rectangular parallelepiped. The electrode plates Pb1 to Pb1
The terminal portions of Pb (N + 1) are connected to each other every other layer to form a drive electrode Yb1 and a drive electrode Yb2.

A power supply device Sv is provided between the electrodes Yb1 and Yb2 to form a power supply circuit.
By applying an AC signal to the piezoelectric actuator B, the piezoelectric layers Rb1 to RbN expand and contract in the thickness direction, and as a result, the entire piezoelectric actuator B expands and contracts in the length direction and is driven. That is, in the present embodiment, the piezoelectric layers Rb1 to RbN are driven in a vibration mode of thickness vibration that expands and contracts in the same direction as the electric field.

Each of the piezoelectric layers Rb1 to RbN is a thin plate having a predetermined thickness, that is, a rectangular parallelepiped.
b1 to Pb (N + 1) have a rectangular thin plate shape. Further, as in the case of the first embodiment, the piezoelectric layers Rb1 to RbN are made of, for example, a PZT-based piezoelectric ceramic, and a polarization process is performed such that the polarization direction is reversed for each layer. It has been subjected.

In this embodiment, the distortion of the piezoelectric actuator B is detected on one of the drive electrodes Yb1 and Yb2 provided in pairs, for example, on the side surface of the drive electrode Yb1 (that is, on the surface of the piezoelectric actuator B). For this purpose, another piezoelectric body RbS is formed, and this piezoelectric body RbS
Another electrode plate YbS is formed on the substrate.
The two electrode plates Yb1 and YbS and the piezoelectric layer Rb
S and S constitute a sensor unit for detecting distortion generated in the piezoelectric actuator B.

That is, another piezoelectric layer RbS and another electrode plate YbS are sequentially disposed on at least a part of the surface electrode plate (side surface of the drive electrode Yb1) located on the surface of the piezoelectric actuator B, and The (side surface of the drive electrode Yb1), the another electrode plate YbS, and the another piezoelectric layer RbS located therebetween constitute a sensor unit for detecting a distortion generated in the piezoelectric actuator B. When a distortion due to an external force is applied to the piezoelectric actuator B, charges corresponding to the distortion are generated in the piezoelectric layer RbS, and the electrodes Yb1 and Yb
By taking out this electric charge by the measuring means Mv arranged between bS, the distortion generated in the piezoelectric actuator B can be detected.

This piezoelectric actuator B is used in the first embodiment.
By attaching the magnetic disk drive 1 to the main actuator 10 in the same manner as described above, the resonance of the main actuator 10 can be canceled, the bandwidth of the servo system can be widened, and high-speed response can be achieved. Although the above description has been made by taking the magnetic disk drive 1 as an example, the piezoelectric actuator according to the present embodiment is not limited to this. It can be effectively applied to the above-mentioned devices.

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 7 is an explanatory plan view showing a configuration of a part of the main actuator 20 of the magnetic disk drive according to the third embodiment. The main actuator 20 has a configuration similar to that of the main actuator 10 in the first embodiment, except that two piezoelectric actuators are provided. That is, in the present embodiment, a pair of piezoelectric actuators C1 and C2 are attached to both sides of the voice coil 15 that drives the main actuator 20.
As the piezoelectric actuators C1 and C2, those described in the first or second embodiment can be used.

FIG. 8 is a block diagram of the magnetic disk drive for explaining the control method of the main actuator 20 and the piezoelectric actuator of the magnetic disk drive according to the present embodiment. As shown in this figure, output signals from the sensor units (first sensor unit Cs1 and second sensor unit Cs2) of the first and second two piezoelectric actuators C1 and C2 are input to the sensor signal processing unit 17b. You. The sensor signal processing means 17b is provided inside the control circuit element 17. The sensor signal processing means 17b performs difference processing on the two sensor outputs. For this difference processing, a differential amplifier circuit or the like can be used.

Two piezoelectric actuators C1 and C2
Are arranged in pairs on both sides of the voice coil 15 as described above, and are provided substantially symmetrically with respect to the center line of the main actuator 20. For this reason, when distortion occurs that rotates the main actuator 20, 2
One of the two piezoelectric actuators C1 and C2 has a strain in the contracting direction, and the other has a strain in the extending direction. Therefore, the output signal has the opposite phase, and by performing the difference processing between the two, distortion related to rotation can be detected with high sensitivity.

The above-described signal processing is performed by the sensor signal processing means 17b, and the output signal from the sensor signal processing means 17b is input to the control means 17a. The control means 17a outputs drive signals for driving the respective piezoelectric actuators C1 and C2 in accordance with the output signal from the sensor signal processing means 17b, and outputs first and second two piezoelectric actuators C1 and C2. (Specifically, the respective drive units Cd1 and Cd2) are controlled. As described above, by controlling the driving of the two piezoelectric actuators C1 and C2, the resonance vibration accompanying the driving of the main actuator 20 can be more accurately canceled, and the band of the servo system can be expanded.

Although the above description has been made with reference to the magnetic disk drive as an example, the arrangement structure of the piezoelectric actuator according to the present embodiment is not limited to this. The present invention can be effectively applied to other types of apparatuses used.

(Embodiment 4) Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a perspective view of a piezoelectric actuator according to the fourth embodiment. The piezoelectric actuator D includes a plurality of piezoelectric layers Rd1 to Rd4 and a plurality of electrode layers Pd1 to Pd1.
d5 are alternately stacked in the thickness direction of the piezoelectric actuator D, and have a configuration similar to that described in the first embodiment (see FIG. 1), but the uppermost electrode plate Pd1 in the figure. Is divided into two parts.

That is, in this embodiment, the uppermost electrode plate Pd1 is divided along the longitudinal direction of the piezoelectric actuator D into two, an electrode plate Pd1 ′ and an electrode plate Pd ″. Electrode plate Pd1 'and electrode plate P
d ″, together with the lower electrode plate Pd2 and the piezoelectric layer Rd1 sandwiched between them, constitute a sensor unit for detecting distortion generated in the piezoelectric actuator D. That is, the piezoelectric actuator D has 2 This means that the two strain detection units are formed side by side.

FIG. 10 is a block diagram showing a main actuator system and a method of controlling the piezoelectric actuator in the magnetic disk drive using the piezoelectric actuator D described in FIG. The main actuator and the magnetic disk device in which the piezoelectric actuator is incorporated are the same as those in the first embodiment (see FIGS. 2 and 3), and further description will be omitted. The piezoelectric actuator D is provided with two sensor units (a first sensor unit Ds1 and a second sensor unit Ds2), and can detect distortion accompanying rotational vibration generated in the main actuator.

That is, when distortion due to rotation is applied to the piezoelectric actuator D, the magnitude of the distortion is different between the left and right of the axis of symmetry indicated by the broken line of the piezoelectric actuator D. Therefore, the sensor portions Ds corresponding to these left and right portions, respectively.
The distortion of the rotation component can be detected by subjecting the output signals from Ds1 and Ds2 to differential processing.

As shown in FIG. 10, two sensor units Ds
1 and Ds2 are input to the sensor signal processing unit 27b. In the sensor signal processing unit 27b, the sensor units Ds1,
The result of differential processing of the output signal from Ds2 by a differential circuit or the like is transmitted to the control means 27a. Control means 27a
Transmits a signal for driving the piezoelectric actuator D to the driving unit Dd of the piezoelectric actuator D based on the signal from the sensor signal processing unit 27b so as to cancel the resonance of the rotational component of the main actuator. As described above, even when only one piezoelectric actuator is provided, by providing two sensor units Ds1 and Ds2 in this one piezoelectric actuator D, resonance can be canceled more accurately with respect to the rotational component. Was.

The piezoelectric actuator used in the magnetic disk device according to the present embodiment includes a piezoelectric actuator (see FIG. 6) in which a piezoelectric layer and an electrode plate are laminated in the longitudinal direction so as to utilize thickness vibration. One provided with two sensor units may be used. In this case, as shown in FIG. 11, one of the drive electrodes Ye1 and Ye2 provided in a pair, for example, the side surface of the drive electrode Ye1 (that is,
Another piezoelectric layer ReS is formed on the surface of the piezoelectric actuator E) for strain detection of the piezoelectric actuator E, and another electrode plate Ye is formed on the piezoelectric layer ReS.
S is formed, and these two electrode plates Ye1 and YeS and the piezoelectric layer ReS constitute a sensor unit for detecting a distortion generated in the piezoelectric actuator E. The outermost portion of the sensor unit (that is, the piezoelectric actuator E) The above another electrode plate YeS located at the outermost side of the side surface) may have an upper and lower two-part structure in which the another electrode plate YeS is divided into an upper electrode plate YeS1 and a lower electrode YeS2.

In the above description, the magnetic disk drive 1 is taken as an example. However, the piezoelectric actuator according to the present embodiment is not limited to this, and an actuator requiring positioning is used. The present invention can be effectively applied to other types of devices.

(Embodiment 5) Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 12A is a perspective view of a piezoelectric actuator according to the fifth embodiment, and FIG. 12B is an explanatory view schematically showing a cross-sectional structure of the piezoelectric actuator and a driving mechanism. Piezoelectric actuator F according to the fifth embodiment
Represents a plurality of piezoelectric layers Rf1 to Rf3 and a plurality of electrode plate layers P
f1 to Pf4 are alternately stacked in the thickness direction of the piezoelectric actuator F, and have the same structure as the piezoelectric actuator J according to the conventional example described with reference to FIG. Note that the main actuator and the magnetic disk device in which the piezoelectric actuator is incorporated are the same as those in the first embodiment (see FIGS. 2 and 3), and further description will be omitted.

As described above, the piezoelectric actuator F of the present embodiment is not provided with the sensor unit for detecting the distortion generated in the piezoelectric actuator F, but the driving unit itself of the piezoelectric actuator F is used as the sensor unit. You. That is, the switching means 37c is provided between the drive electrode Yf1 and the drive electrode Yf2, and the drive electrode Yf1 and the drive electrode Yf2 are provided.
2 is connected to a driving signal source 38 (driving source),
Alternatively, the connection with the sensor signal detection means 39 can be switched and selected. The control means 37a in the control circuit element 37 determines which connection is to be made, and the control means 37a controls the switching means 37c.

The switching means 37c is provided, for example, in the control circuit element 37. The driving signal source 38 is more preferably attached to the above-described power supply device Sv.
Corresponds to the aforementioned measuring means Mv.

When the main actuator is driven to cause resonance vibration when the switching means 37c is switched to the sensor signal detecting means 39 side, the whole piezoelectric actuator F detects distortion as a sensor part. Control means 37a
After the connection is switched to the drive source 38 side by the switching unit 37c, a drive signal is transmitted to the drive source 38 in accordance with the output signal of the sensor signal detection unit 39, and the piezoelectric actuator F is driven to generate resonance vibration. Can be countered.

As described above, the resonance of the main actuator can be canceled by the piezoelectric actuator F and the frequency bandwidth of the servo system can be widened by providing the switching means 37c without providing the sensor section in the piezoelectric actuator F itself. , And a high-speed response was enabled. As the piezoelectric actuator used in the magnetic disk device according to the present embodiment, the conventional actuator described with reference to FIG. 14 can be used similarly.

[0058]

As described above, according to the present invention, the resonance vibration accompanying the driving of the main actuator of the disk recording device is detected by the sensor section provided in the piezoelectric actuator, and the piezoelectric signal is detected based on the output signal. The resonance vibration can be canceled by driving the actuator. Thus, it is possible to provide a magnetic disk device having a wide frequency range of the servo system and capable of high-speed response.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing a configuration of a piezoelectric actuator according to a first embodiment of the present invention.

FIG. 2 is an explanatory plan view schematically showing a configuration of a main part of a main actuator according to the first embodiment.

FIG. 3 is an explanatory plan view schematically showing a configuration of a main part of the magnetic disk device according to the first embodiment.

FIG. 4 is a block diagram illustrating a method for controlling the magnetic disk drive according to the first embodiment.

FIG. 5 is a Bode diagram showing resonance characteristics of the main actuator according to the first embodiment.

FIG. 6 is an explanatory view schematically showing a configuration of a piezoelectric actuator according to a second embodiment of the present invention.

FIG. 7 is an explanatory plan view schematically showing a configuration of a main part of a main actuator according to a third embodiment of the present invention.

FIG. 8 is a block diagram illustrating a method for controlling a magnetic disk drive according to the third embodiment.

FIG. 9 is a perspective view schematically showing a configuration of a piezoelectric actuator according to a fourth embodiment of the present invention.

FIG. 10 is a block diagram illustrating a method of controlling a magnetic disk drive according to the fourth embodiment.

FIG. 11 is a perspective view schematically showing a configuration of another piezoelectric actuator according to the fourth embodiment.

FIG. 12 is an explanatory view schematically showing a configuration and a control method of a piezoelectric actuator according to a fifth embodiment of the present invention.

FIG. 13 is an explanatory view schematically showing a configuration of a piezoelectric actuator according to a conventional example.

FIG. 14 is an explanatory diagram schematically showing a configuration of a piezoelectric actuator according to another conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk drive 5 ... Voice coil motor 7, 17, 27, 37 ... Control circuit element 10, 20 ... Main actuator 11 ... Actuator main body 12 ... Head 13 ... Suspension 14 ... Support arm 15 ... Voice coil 17a, 27a, 37a ... Control means 17b, 27b ... Sensor signal processing means 37c ... Switching means A, B, C1, C2, D, E, F ... Piezoelectric actuators As, Cs1, Cs2, Ds1, Ds2 ... Sensor parts Dm ... Magnetic disks Pa1 to Pa5 , Pb1 to Pb (N + 1), Pd1 to Pd
d5, Pf1 to Pf4, YbS, YeS ... Electrode plates Ra1 to Ra4, Rb1 to RbN, Rd1 to Rd4, R
f1 to Rf3, RbS, ReS: Piezoelectric layer Ya1, Ya2, Yb1, Yb2, Yd1, Yd2, Y
e1, Ye2, Yf1, Yf2 ... drive electrodes

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsunori Morikiki 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5D042 MA15 MA20 5D068 AA01 BB01 CC12 EE01 GG03

Claims (9)

[Claims] 1. A piezoelectric actuator comprising a piezoelectric element in which a plurality of piezoelectric layers and a plurality of electrode plates are alternately stacked, wherein a part of the plurality of piezoelectric layers and a part of the plurality of electrode plates are provided. A piezoelectric actuator characterized in that a sensor part for detecting a distortion generated in the piezoelectric actuator is partially configured. 2. A piezoelectric actuator comprising a piezoelectric element in which a plurality of piezoelectric layers and a plurality of electrode plates are alternately laminated, wherein at least a part of a surface electrode plate located on a surface of the piezoelectric element is provided. Another piezoelectric layer and another electrode plate are disposed in order, and the distortion generated in the piezoelectric actuator is detected by the surface electrode plate, the another electrode plate, and the another piezoelectric layer located therebetween. A piezoelectric actuator, comprising: 3. The piezoelectric actuator according to claim 1, wherein two sensor units for detecting the distortion are provided. 4. A head for recording information on a disk and / or reading information recorded on the disk, a suspension for supporting the head, and a rotationally oscillating support arm for supporting the suspension. Having a main actuator for moving the head
The piezoelectric actuator according to any one of claims 1 to 3 is provided, and the driving of the piezoelectric actuator is controlled to reduce mechanical vibration generated when the main actuator is driven. Disk recording device. 5. The disk recording apparatus according to claim 4, comprising a plurality of the piezoelectric actuators according to claim 1 or 2. 6. A head for recording information on a disk and / or reading information recorded on the disk, a suspension for supporting the head, and a rotationally oscillating support arm for supporting the suspension. Having a main actuator for moving the head
When controlling the operation of a disk recording device provided with the piezoelectric actuator according to claim 1 or 2,
A drive for controlling the piezoelectric actuator based on an output signal from a sensor unit for detecting a distortion of the piezoelectric actuator, thereby reducing a mechanical vibration generated when the main actuator is driven. Method. 7. A head for recording information on a disk and / or reading information recorded on the disk, a suspension for supporting the head, and a rotationally oscillating support arm for supporting the suspension. Having a main actuator for moving the head
In controlling the operation of the disk recording device having the piezoelectric actuator according to claim 3, the piezoelectric actuator is driven and controlled based on a signal obtained by subjecting the output signals from the two sensor units to differential processing. A method for controlling a disk recording device, characterized in that mechanical vibration generated when an actuator is driven is reduced. 8. A head for recording information on a disk and / or reading information recorded on the disk, a suspension supporting the head, and a rotationally oscillating support arm supporting the suspension. Having a main actuator for moving the head
When controlling the operation of a disk recording apparatus having two piezoelectric actuators according to claim 1 or 2, output signals from sensor units for detecting distortions of the two piezoelectric actuators are subjected to differential processing. A method for controlling a disk recording device, comprising: controlling driving of the piezoelectric actuator based on a signal to reduce mechanical vibration generated when the main actuator is driven. 9. A head for recording information on a disk and / or reading information recorded on the disk, a suspension for supporting the head, and a rotationally oscillating support arm for supporting the suspension. Having a main actuator for moving the head
When controlling the operation of a disk recording device provided with a piezoelectric actuator having a piezoelectric element in which a plurality of piezoelectric layers and a plurality of electrode plates are alternately stacked as an auxiliary actuator, in accordance with strain generated in the piezoelectric actuator, An output signal to be generated and a signal from a drive source for driving the piezoelectric actuator are switched to be detectable,
A method for controlling a disk recording apparatus, comprising: controlling drive of the piezoelectric actuator based on an output signal generated in accordance with the distortion to reduce mechanical vibration generated when driving the main actuator.